ETV4 potentiates nuclear YAP retention and activities to enhance the progression of hepatocellular carcinoma

Dysregulation of the Hippo pathway that promotes cell survival, proliferation and tumorigenesis, relays on the coordinated interactions of YAP with the factors that determine YAP translocation and the related transcriptional programming. Here, we demonstrate that ETV4, a transcriptional factor participating in various protumorigenic processes, enhances YAP-mediated transactivation and hepatocellular carcinoma (HCC) progression. Mechanistically, the enhancement of YAP activities is mediated by the interaction between ETV4 and YAP, which not only increases nuclear YAP accumulation but also directly augments the YAP/TEAD4-mediated transcriptional activation in tumor cells. Functionally, the interplay of ETV4 and YAP promotes growth of liver tumor cells, and activates the genes related to myeloid cell recruitment, including CXCL1 and CXCL5, leading to an enriched presence of myeloid-derived suppressive cells and macrophages but a decreased infiltration of T cells and NK cells in transplanted tumors. More importantly, the correlations between YAP activation, the altered immune cell distribution and ETV4 expression are observed in human HCCs. Therefore, our study reveals a functional interaction between ETV4 and YAP that contributes to HCC progression, and provides mechanistic insights into the regulation of nuclear YAP retention and transactivation.